


Rue Ryuzaki: L or B?

by BusyBizzy114



Category: Death Note (Anime & Manga)
Genre: Beyond Birthday Being Creepy, Beyond Birthday is His Own Warning, But is also not one, Gen, L (Death Note) is a Dick, L is a troll, Matsuda Touta Is An Idiot, Yagami Light is Kira, Yagami Light is a Dick
Language: English
Status: In-Progress
Published: 2020-04-23
Updated: 2020-07-05
Packaged: 2021-03-02 03:06:31
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 2,703
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/23798158
Author URL: https://archiveofourown.org/users/BusyBizzy114/pseuds/BusyBizzy114
Summary: It was Matsuda who first noticed. L ate too much for one person, didn't sleep at all, and was seen in more than one room at once. Once he told Light, the pieces came together. How L sometimes didn't remember what he was told yesterday, his attitude changes, and how sometimes, his eyes looked red.Or a story in which L and B work together to pretend to be one (1) insomniac detective when there are actually two (2) of them, until eventually someone else realizes that HEY! there's no way only one person could survive all that.
Relationships: Beyond Birthday & L, L & Yagami Light
Comments: 9
Kudos: 55





	1. Prologue: Matsuda's discovery

Matsuda was no genius. He knew this, and accepted that he would never be as smart as Ryuzaki, or even Light, who by all means, should have been his subordinate, just by age. (His only condolence was that Light seemed to be smarter than the rest of the Task Force, including his own father, at least based on the way Ryuzaki and Watari treated him.) Matsuda was never top of the class growing up. He was never the lowest in the class either. He was simply….average. He was average enough, and only made it into the task force because he was too average to be a dirty cop, and cared just enough to risk his life on the case.

He wanted to become a police officer to help people, and while it hurt his ego to be so easily dismissed (“Matsuda’s acting stupid again”) he was willing to be sidelined as MisaMisa’s manager, or used as an errand boy as long as it meant he could help. Because maybe he couldn’t solve the case. But Ryuzaki could, and Matsuda would do everything in his power to help him.

Matsuda looked up to, and respected Ryuzaki with his intelligence, and respected (and was jealous) of Light, who seemed to earn Ryuzaki’s respect despite being the main suspect. Despite how much Matsuda looked up to Ryuzaki and his own averageness, he was still the first person to realize that something about Ryuzaki was not quite.... Right.  
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Ryuzaki never slept. That was something that everyone in the Task Force knew, and something that Light would often complain about during his time handcuffed to the detective. The bags under his eyes only emphasized this, and in itself, didn’t seem like a big deal. It wasn’t until one Friday when Light was sleeping from working on the Kira case overnight with Ryuzaki, and Ryuzaki was acting normal that Matsuda wondered When did he sleep? 

He had to sleep at some point right? It was only human of him too. It must have been when Light fell asleep, and he fell asleep after him due to his fear of the suspect, or from his sugar high. 

Matsuda ignored the curiosity that welled up, begging him to just ask the detective, he already knew what the response would be: “Don’t ask stupid questions Matsuda”. Besides, if it was a big deal, someone else in the Task Force would have noticed or asked…..right?

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Ryuzaki was a mess. That was clear from the lack of shoes, the bad posture, messy clothes and terrible eating habits. If by the off chance Matsuda had somehow missed those major signs, then the whispered judgements about his appearance that Aizawa made would have clued him in. 

Everyday, Light was unhandcuffed briefly to take a shower, Ryuzaki would still be in the bathroom, much to Light’s very vocal dismay, but wouldn’t be looking. This was the only time that the two had been separated according to Light. Light took a shower. Ryuzaki did not. 

When did Ryuzaki clean? While he was clearly not the biggest advocate of hygiene, he didn’t smell. He had to take a shower at some point. If he did it at night when Light was asleep, then that took away even more potential time for him to sleep himself. Light probably didn’t think anyone would need to know about when Ryuzaki took a shower. Matsuda never asked. He was just being stupid again. 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Ryuzaki ate a lot. He was always eating an obscene amount of sugar, and it never seemed to end. (Personally Matsuda was worried that if he died from a heart attack, there would be no way to know if it was Kira or the sugar that took him out). 

He ate more than enough for one person, and never got sick. When Matsuda would come in early to drop off files, he was eating. Late at night, he was eating. When they would work on catching Kira, he was eating. When interrogating MisaMisa, he was still eating. 

He was always eating, and he never gained any weight, and Matsuda knew that his excuse about thinking couldn’t be correct because Light ate a normal amount and he was very smart too. At one point, Matsuda saw an entire dessert tray big enough for a party, and before lunch time Ryuzaki had eaten all of it. That…..wasn’t human. 

Matsuda felt like he was overthinking it (which was ironic as the dumbest member) and didn’t say anything. It wasn’t until the final clue that pieces began to fall into place.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Ryuzaki was everywhere. On Friday, Matsuda gave Ryuzaki his coffee, then went to the bathroom, still holding his own. Matsuda was busy thinking about the Kira case, and if Light and Ryuzaki were right in their theories, that meant that Kira did give away his power, or there was another Kira? Would there continue to be more and more Kiras? Why was the power suddenly popping--

His train of thoughts were stopped when he ran into Ryuzaki, spilling his coffee all over his shirt. After apologizing, and dealing with Ryuzaki’s unimpressed stare, Matsuda ran back to the conference room to find paper towels only to find Ryuzaki there surrounded by the task force with an unstained shirt. It was like he never ran into Matsuda. 

At this point, Matsuda was willing to look like an idiot if it meant his questions were answered. Well, willing to look like an idiot to Light at least.  
He would find out what Ryuzaki was hiding. Something wasn’t right.

**Notes for the Chapter:**

> L is my favorite character for no other reason than I normally love detectives, and Light lost my support the moment he started killing non-criminals. If anyone wants to have a moral debate with me about team L vs Light I am always down because despite my Raccoon boy not always being the best, I truly believe that he was the hero of Deathnote. Matsuda is the most “pure” character though, who has an emotional intelligence that L and Light both seem to lack. I wasn’t planning on writing the prologue from his opinion but it sort of happened, and he’s underappreciated so I figured why not. It’s just a weird headcanon that I had that L and B would totally switch places all the time after B looked like him, and that L lies about the % and know that Light is/was (the whole Yostuba arc is confusing) Kira and normally I don’t write fics, but quarantine has given me nothing but time. Anyway, pls leave a comment or kudo!


	2. When Light sees the Light

**Summary for the Chapter:**

> In which Light is shooketh

Matsuda was an idiot. Half the time Light didn’t even know how he qualified to be on the Task Force. Everyone except L seemed incompetent, but Matsuda especially so. Half the time Matsuda seemed like he couldn’t catch a general crook. Half the time Light wanted to yell at him to shut up. 

But Light was the perfect son, perfect student and perfect friend. 

So he smiled, and encouraged Matsuda. Listened to his stupid theories, and his incessant chatting that never seemed to stop. Light didn’t understand why L kept him on the task force. He could easily be replaced, and didn’t provide anything that a regular coffee boy or manager couldn’t do. 

But despite his internal thoughts about Matsuda, he had a reputation to uphold, and it was always good to have Matusuda see him as nothing more than a helpful innocent school boy (he thought he was, but no he was Kira and L had to go). This is why, when Matsuda pulled him aside, and asked for his opinion, Light gave him a smile (picture perfect, as usual) and took on the tone of a concerned friend. Light listened. 

And his world shifted. 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

How had Light never noticed. And how had MATSUDA of all people noticed first. Light had just gotten so used to L’s eccentric habits that he never really thought of how by all means, it should have been impossible. There was no possible way that L had never actually slept, he had to have at some point, and he had to have cleaned himself at one point. He was scared when he found out that shinigami’s were real, was that fake too? How long had L been treating Light like an idiot? Was he working with Ryuk? He knew it. They were conspiring against him and he was….freaking out. 

Breathe.

Matusda was an idiot. Why was Light even taking him seriously? L was human, he would have told Light his name if he wasn’t, but he was and he could be killed by the Deathnote. Matsuda must have been mistaken, except...

True, it wouldn’t be too hard for L to manipulate Matsuda to come to this conclusion. But even then, that didn’t explain the doppelgänger that Matsuda swore he saw, and Matusda wasn’t so stupid as to hallucinate someone as distinctive as L. 

L couldn’t have known. L couldn’t prove he was Kira. L was annoying, but he was only an obstacle for Kira’s plan. This wasn’t a bad thing. This could be good. L was hiding something, he had to be hiding it for a reason. Every move the detective made was calculated and thought out. He didn’t want Light to know something, which meant that it could be what would finally allow him to win this mental battle and chess between them. 

What was he hiding? 

The detective in question was staring at him with his black eyes, as he entered the room. Light tried to shake off the feeling of the eye’s dissecting him, as if he was nothing but a puzzle to solve. Light pushed down the anger at being treated like a lab rat and did his best to look unassuming and innocent and like L’s friend (his only friend).

“Light-kun, your chance of being Kira has increase by 1.2%” 

Light was poised. Light was perfect. Light did not lose his temper. Light was currently yelling at L for accusing him of being Kira when there were more important things to worry about. Damn it. Of course L knew all of the ways to piss him off. 

“Hmm...such rash behavior coming from you is uncouth, what would your father say”

This pissed off Light even more. L of all people had no right to lecture him of proper etiquette. He could barely take care of himself for goodness sake. But it also pissed off his dad, and reminded him there are people watching, they are watching you, you are an innocent kind student. 

Unclenching his fists, and breathing out his anger, Light put on his best sheepish smile. “Sorry Ryuzaki, I guess I’m just a little tired”

“If Light-kun needs to sleep I understand”

There. He could try and figure out when L slept now. Even if his actions were transparent and were clearly searching for information, he could always explain it away as a worried friend. 

“I’ll probably go to bed soon, you should too. Even you need sleep.”

Now L had to address sleep in some way, and even if he didn’t respond, the other members of the task force would now think about it.

L tilted his head at him, eating another cookie.

“Who said that I need to sleep Light-kun?”

That was not the response that Light wanted. How could this man (the genius) miss all of the social cues. Of course L would give a response that didn’t make sense, and didn’t answer his unspoken question. L may not know how to play the game of socializing, but Light did. 

“Good joke Ryuzaki! I get i-”

“It wasn’t a joke”

Silence. How was Light supposed to respond. Out of the corner of his eye, Light could see the rest of the task force looking at L, but L was staring at Light. Unblinking, not moving other than to eat another damn cookie. 

Damn L. This was a declaration. Forget killing him, Light would expose L and whatever he was hiding first. So gone in his anger, he couldn’t remember what he said to smooth over the conversation. All he could remember was the bleeding edges of red, and Ryuk’s incessant, annoying laughter. Except, even with his vision red with anger, did L’s eyes just flash red at him?

**Notes for the Chapter:**

> I'm actually struggling to write L the most because so little is known about him canonically, and trying to keep him in character, while still making him basically prank the Task Force, is really hard. He's such a contradiction. Some of you may disagree with how emotional Light is, but I think his emotion is really what allowed him to take such large risks, and feel justified in his actions, without thinking them through, but still feel a need to seem perfect. Nobody cares that much about how others view them unless they are insecure/emotional in some way. Anyway, thanks for reading the chapter and this note, please leave a kudo or comment, it really means a lot.


	3. In which Light has a internal breakdown

**Summary for the Chapter:**

> In which Light sees all of the right clues but makes the wrong conclusions

Light asks Ryuk.   
The ideal time to figure out L’s secret would have been when they were handcuffed together. How could he not have noticed, even if his memories were erased?! No time to dwell on that now, Light thought, it was better to not solve the secret then if it meant that his innocence was proved to the task force. 

Besides, even if he couldn’t add cameras to observe L as L had done, he had a secret weapon: Ryuk. 

Said secret weapon was currently making a fool of himself as he flew around the task force cackling in the air. It was only from constant exposure to Ryuk that Light managed to school his face to not react.

Despite promising apples for the information earlier, which Ryuk eagerly agreed to, whatever he found he was unwilling to say. Light couldn’t question him in front of the task force, but had to suffer Ryuk saying “now this is real entertainment” over and over again.

If L’s eyes flashed red because they were like Misa’s then there was a good chance he knew that Light was Kira because of the lack of numbers over his head. But if that were the case, why didn’t he simply confront him about it earlier? And it still didn’t explain the “not human” aspects that Matsuda noticed. 

Light calculated two likely probabilities.

The first was that L had never shown his true face. His appearance was almost comical, and he played the trick with Lind L. Taylor. What was to stop him from making others take on the same appearance, that was dramatic enough to cover up small differences in traits, and watch and order them to say certain things through a secret way? It would make sense, he knew Kira could kill with a name and a face, so to ensure his own safety he never appeared. The actors most likely switched out when Light slept and he never knew. This would mean that L was playing Light the entire time, and he never had a real shot at killing him, and if that were the case, then Kira’s victory just got increasingly harder. 

The second was that L may not be entirely human. While the option may have seemed unlikely, the chance that Light would have believed in shinigami a year ago was just as unlikely. If shinigami were real, then what was there to stop other beings from being real as well, and he clearly couldn’t trust Ryuk’s word, he was only there for entertainment, and what would be more entertaining than Light being blindsided. There was still a chance that the Deathnote could kill him however if that was the case.

A third option (that Light wanted to pretend was not an option) is that the stress of trying to outsmart L was getting to him and he was imagining things and blowing them out of proportion. He never took Matsuda seriously, it could be the constant mind games getting to him. But- as the God of the new world that most certainly wasn’t possible, and definitely would never happen. 

Light would just have to figure out himself if there were multiple actors or if L wasn’t human. The trick was to ask for a response to something that the real L wouldn’t find important enough to direct a predetermined response, with an immediate answer required. 

If he could just ask something he already had an answer for.

“Light-kun, are you okay? Are you feeling sick? Oh I know, I should give you some chocolate to feel better!”

It was then that Light realized that, while he had managed to successfully ignore Ryuk, he also ignored the rest of the conversation the task force was having around him. This, while embarrassing, had given him an idea and a way to test his theory.

“Thanks L, I guess I didn’t realize how tired I was” taking the chocolate that was being offered to him “hey, I guess it never really occurred to me before, but what’s your favorite sweet?”

Cake. That’s what L should say, it was his favorite food from what Light had seen.

“I guess my favorite candy would be, a lollipop”

Maybe L thought he meant candy? But still, he said Lollipop with a flourish. Was there a possible double meaning? Or was Light getting paranoid and not thinking it through?

“What about your favorite food in general then?”

“Hmm. Why is Light-kun suddenly so interested in my tastes? Oh! Are you planning on getting me a gift? In which case, I want strawberry jam” he responded, his tone monotonous.

That was not what he was expecting. L was human, but that meant that he definitely had hired actors. At that moment, L looked directly at him, and his eyes turned red, in a way that only Misa’s had when she had the shinigami eyes. 

Shit.

**Notes for the Chapter:**

> Lol, I only wrote this because I was waiting for another story to update, and was like, maybe I should update mine. I'm not really good at trying to mimic their personalities and the writing style changed, but while I cannot garuntee when I'll update, I'll try to.


End file.
